1. Field of the Invention
The present invention relates to a multilayer insulating film of a semiconductor device deposited with insulating films such as an interlayer film and cover film and to a method for forming the film.
2. Description of the Related Art
A semiconductor device uses a structure in which a semiconductor active element or aluminum interconnection is covered with an insulating film or the semiconductor circuit is entirely protected with the insulating film.
For example, there are some multilayer interconnection structures in which aluminum interconnection is covered with a silicon oxide film, an SOG film is deposited on the silicon oxide film to smooth the surface, a PSG film is deposited on the SOG film, and aluminum interconnection is formed on the PSG film and covered with a silicon nitride film.
However, when a semiconductor circuit chip is wire-bonded with leads and then they are covered with a resin package into a finished product to apply a high-temperature humidification test to the finished product, insulating films such as a PSG film and an SiN film of the semiconductor circuit may peel off each other at the probability of approx. 1/10,000.
It is estimated that the above phenomenon depends on an insulating material serving as a substrate, leaving time of an insulating film in the atmosphere, treatment method for deposition of the film, change of stress due to hygroscopicity of the film, or design pattern.
However, peeling of the insulating film under the high-temperature humidification test rarely occurs. Also, it rarely occurs in actual products. Therefore, the cause of the phenomenon is not clarified. However, if peeling of the insulating film should occur, there is a problem that the reliability is lost.